Three-dimensional ppy-mxene composite aerogel based on metal salt ice crystal polymerization cross-linking and preparation method thereof

Abstract

The application belongs to the technical field of energy storage materials, and particularly relates to a three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization cross-linking and a preparation method thereof. By using Py and FeCl3 ice crystals and by controlling the melting of the ice crystals, the speed of the polymerization reaction is finally controlled, and PPy and Fe 2+ are slowly combined to generate PPy and Fe 2+ , which can be uniformly dispersed in the interior of the composite material, cross-linking MXene layers generate an excellent porous network structure, and the generated PPy effectively reduces the tendency of oxidation of MXene. Finally, the super-light three-dimensional PPy-MXene composite aerogel is obtained through freeze-drying. The three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization cross-linking has super-hydrophilicity, so that electrolyte ions can quickly pass through, realizing fast charging and discharging. Its excellent cycle stability and high energy and power density make it have broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage materials technology, specifically relating to a three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking and its preparation method. Background Technology

[0002] With the energy crisis becoming increasingly serious, the demand for high-performance energy storage devices is urgent. Three-dimensional structures possess large specific surface areas, high structural stability, and high density of active sites, enabling faster ion transport rates and higher energy densities. Conductive polymers exhibit good conductivity, flexibility, and ease of synthesis, while carbon-based nanomaterials possess high specific surface areas, low weight, controllable pore size distribution, and compatibility with other materials. Conductive polymers such as PPy undergo significant volume expansion and contraction during charge / discharge, leading to structural decomposition, rapid capacitance decay, and limited cycle life. Ti3C2T x The introduction of nanosheets alleviated the expansion problem of PPy during charging and discharging, and promoted the growth of Ti3C2T. x The structural stability of PPy composites is improved. Introducing PPy with pseudocapacitive properties results in a higher capacitance than pure MXene. The -F and other groups on the MXene surface give the MXene nanosheets good hydrophilicity. This provides more nucleophilic reaction sites for the polymerization of pyrrole monomers and also facilitates Fe... 2+ Eliminating the electrostatic attraction between MXene and NS provides the necessary prerequisites. However, if the polymerization rate is not controlled, the internal structure of the polymerized material will become uneven, and crosslinks will aggregate at certain locations. Therefore, it is necessary to control the reaction rate of pyrrole monomers with ferric chloride to control the formation of polypyrrole and ferrous chloride, thereby controlling the polymerization rate. Summary of the Invention

[0003] The purpose of this invention is to provide a three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization and crosslinking, and its preparation method. Ferric chloride is designed and prepared into metal salt ice crystals. The melting of the ice crystals is controlled at a certain temperature, thereby controlling the rate of polymerization to obtain a uniformly crosslinked three-dimensional PPy-MXene composite aerogel. PPy and MXene are composited through metal salt ice crystal polymerization and crosslinking to prepare a three-dimensional porous structure, achieving higher energy density.

[0004] To achieve the above objectives, this invention provides a method for preparing a three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking, comprising the following steps:

[0005] Step 1: Using Ti3AlC2 as raw material, the initial product was synthesized by etching with HCl and LiF for 30-35 hours. The obtained initial product was centrifuged to remove the lower precipitate, washed, and then sonicated. The supernatant was centrifuged to obtain Ti3C2T with pH 5-6. x MXene solution;

[0006] Step 2: Take a certain amount of MXene, add water and ethanol to obtain an MXene solution of a preset concentration, then add pyrrole and ferric chloride ice crystals, react for 6-10 hours to obtain PPy-MXene composite hydrogel;

[0007] Step 3: Immerse the PPy-MXene composite hydrogel in ultrapure water to remove excess salt, take out the composite hydrogel and pre-treat it by absorbing water on filter paper, then fully cool it in liquid nitrogen and freeze-dry it to finally obtain a three-dimensional PPy-MXene composite aerogel with metal salt ice crystal polymerization and cross-linking.

[0008] Furthermore, the reaction temperature in step 1 is 30-40℃, and the freeze-drying temperature in step 3 is -50 to -60℃.

[0009] Furthermore, in step 2, the volume ratio of water to ethanol is 4:1.

[0010] Furthermore, in step 1, Ti3C2T x The concentration of the MXene solution is 12 mg / ml to 22 mg / ml; the concentration of the MXene solution prepared in step 2 is 12 mg / ml.

[0011] Furthermore, the ferric chloride ice crystals are obtained by freezing a ferric chloride solution.

[0012] Furthermore, the ferric chloride ice crystals are added at 0-5°C.

[0013] Furthermore, the mass ratio of MXene to pyrrole is 1:(1.2-1.7); the mass ratio of MXene to FeCl3 is 8:(2-4).

[0014] The present invention also provides a three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking obtained by any of the above preparation methods.

[0015] The present invention also provides an electrochemical device prepared from the three-dimensional PPy-MXene composite aerogel described above.

[0016] Furthermore, the electrochemical device is obtained through laser shaping technology, wherein the laser shaping uses an infrared laser, is carried out in an inert atmosphere, and the power of the laser shaping is 30W.

[0017] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0018] A three-dimensional PPy-MXene composite aerogel synthesized by metal salt ice crystal polymerization and crosslinking via a simple experimental method exhibits excellent pore structure, enabling rapid charge-discharge and demonstrating high energy and power densities. Its superior structure contributes to its excellent mechanical properties; its morphology remains virtually unchanged after being loaded with a 500g weight, and it can be fabricated in large sizes, indicating its potential for integration and promising applications in practical production. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process for preparing PPy-MXene composite aerogels in Examples 1-3 of the present invention;

[0020] Figure 2 SEM images of PPy-MXene with different MXene and Py ratios prepared in Example 2;

[0021] Figure 3 TEM and HRTEM images (c) of MXene (a) and PPy-MXene (b) prepared in Example 3, and mapping image (d) of PPy-MXene;

[0022] Figure 4 This is a schematic diagram of the contact angle of the self-supporting PPy-MXene composite material in the aerogel state prepared in Example 3;

[0023] Figure 5 These are XRD patterns of the three-dimensional self-supporting PPy-MXene composite aerogels prepared in Examples 1-3;

[0024] Figure 6 This is a schematic diagram comparing the reaction times of Example 2 with and without pyrrole;

[0025] Figure 7 This is an XRD pattern of the reaction time in Example 2 with and without pyrrole;

[0026] Figure 8 The mechanical properties of the three-dimensional self-supporting PPy-MXene composite aerogel prepared in Example 3 are shown in the figure.

[0027] Figure 9 This is the stress variation curve of the three-dimensional self-supporting PPy-MXene composite aerogel prepared in Example 3;

[0028] Figure 10 This is a schematic diagram of the large-size three-dimensional self-supporting PPy-MXene composite aerogel prepared in Example 3;

[0029] Figure 11 This is a graph showing the electrochemical performance of the three-dimensional self-supporting PPy-MXene composite aerogel prepared in Example 3. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0031] The devices used in the following examples include:

[0032] Scanning electron microscope (SEM): JEOL JSM-7001F;

[0033] Transmission electron microscope (TEM): JEM-2100PLUS;

[0034] X-ray diffractometer (XRD): Rigaku ULTIMALV, Japan;

[0035] Raman spectroscopy analyzer: Horiba iHR-320 Raman spectroscopy analyzer, excitation wavelength 532nm;

[0036] Electrochemical workstation: Shanghai Chenhua CHI 760E, China.

[0037] Example 1: Preparation of MXene

[0038] (1) Place 80 mL of HCl solution (9 mol / mL) into a polytetrafluoroethylene (PTFE) reactor, add 4 g of LiF and stir until completely dissolved. Slowly add 4 g of Ti3AlC2(MAX) over 0.5 h. Transfer the PTFE reactor to an oil bath and stir at 35 °C for 30-35 h. Add 100 mL of ultrapure water to terminate the reaction. Centrifuge the reaction solution at 3500 rpm for 5 min, discard the supernatant, and leave the lower precipitate. Repeat centrifugation and washing of the lower precipitate several times until the pH of the solution is close to neutral (pH = 5-6). Sonicate at 70% power for 1 h, then centrifuge at 3500 rpm for 1 h and collect the supernatant to obtain a monolayer or few-layer MXene dispersion.

[0039] (2) Take a certain amount of MXene dispersion and calibrate it by vacuum filtration or freeze drying.

[0040] Example 2: Preparation of PPy-MXene composite hydrogel

[0041] (1) Prepare an MXene solution with a concentration of 12 mg / ml according to the concentration of MXene. The concentration was prepared using water and ethanol (volume ratio 4:1). The purpose of using ethanol was to allow pyrrole to be better dispersed when it was added later.

[0042] (2) Take a certain amount of FeCl3·6H2O to prepare a 2.5M FeCl3 solution, and prepare FeCl3 ice crystals by freezing and other external conditions.

[0043] (3) Pyrrole (Py) was added at a mass ratio of MXene to pyrrole of 2:1, 2:3 and 2:4 respectively, and a certain amount of FeCl3 ice crystals was added at a mass ratio of MXene to FeCl3 of 8:3. The reaction was carried out for 6 to 10 hours to obtain PPy-MXene composite hydrogel.

[0044] Example 3: Preparation of large-size PPy-MXene composite materials

[0045] (1) Take out the PPy-MXene composite hydrogel after the reaction is completed and immerse it in ultrapure water, changing the water several times until the solution is clear and transparent.

[0046] (2) After taking out the PPy-MXene composite hydrogel, placing it on filter paper to absorb the moisture, and then freeze-drying it for 12 hours, the PPy-MXene aerogel was obtained.

[0047] (3) Prepare large-size PPy-MXene composite materials.

[0048] Example 4

[0049] The composite material was laser-plasticized in an argon atmosphere, and after interdigitated encapsulation, electrochemical testing was performed.

[0050] In step (3) of Example 2, the pore size is controlled by adjusting the ratio of PPy-MXene, such as... Figure 2 As shown, this experiment uses a 3:2 ratio (the masses of Py and MXene are respectively).

[0051] according to Figure 3 This demonstrates the successful preparation of MXene and the successful synthesis of PPy-MXene composite materials.

[0052] according to Figure 4 The contact angle image shows that the PPy-MXene composite material described in step (3) of Example 3 has superhydrophilicity, indicating that the electrolyte can be fully wetted. Figure 4 The image showing aerogel on a dandelion demonstrates its ultra-lightweight properties.

[0053] according to Figure 5The XRD patterns show the successful synthesis of the initial MXene material and the successful preparation of the PPy-MXene composite material.

[0054] according to Figure 6 The changes in the reaction over time were compared between adding only FeCl3 and adding both substances. It can be seen that without pyrrole, MXene is gradually oxidized to TiO2 (the bottom gradually turns white) with increasing reaction time. However, no significant change was observed in the vial containing Py with increasing reaction time. This can be further verified by... Figure 7 The XRD pattern shows this.

[0055] The study of the mechanical properties of composite materials in Examples 1-3 is as follows: Figure 8-9 As shown, it can be seen that the morphology of the composite material did not change significantly before and after loading a 500g weight. Figure 8 The material showed no significant damage after being subjected to a stress of 2700 kPa at 80% deformation. Figure 9 ).

[0056] according to Figure 10 The successful large-scale fabrication of this composite material demonstrates its mass production capability and integrability.

[0057] The electrochemical properties of the composite aerogel materials in Examples 1-3 are as follows: Figure 11 As shown, the composite aerogel generated after freeze-drying was laser-shaped under infrared light to create an interdigitated structure. This interdigitated structure was then used to fabricate electrodes, and electrochemical tests were performed on a Chenhua workstation after adding PVAliCl electrolyte. This composite aerogel material exhibits rapid charge-discharge capability and good cycle stability (89.3%), along with excellent power density and energy density at 8 A g. -1 The energy density is 70.3 Wh / kg. -1 The power density is 3892 WKg -1 It has broad development prospects.

[0058] In summary, this invention provides a three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization and crosslinking, and its preparation method. It utilizes Py and FeCl3 ice crystals, and by controlling the melting of the ice crystals, the rate of the oxidative polymerization reaction is ultimately controlled, slowly combining to generate PPy and Fe... 2+ So that Fe 2+The cross-linked MXene sheets can be uniformly dispersed within the composite material, forming an excellent porous network structure. Simultaneously, the generated PPy effectively reduces the tendency of MXene to be oxidized. Finally, an ultralight three-dimensional PPy-MXene composite aerogel was obtained through freeze-drying. This invention, based on a three-dimensional PPy-MXene composite aerogel cross-linked by metal salt ice crystal polymerization, exhibits superhydrophilicity, allowing electrolyte ions to pass through rapidly, achieving fast charge and discharge. Its excellent cycle stability and high energy and power density make it a promising candidate for various applications.

[0059] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking, characterized in that, Includes the following steps: Step 1: Using Ti3AlC2 as raw material, the initial product was synthesized by etching with HCl and LiF for 30-35 hours. The obtained initial product was centrifuged to remove the lower precipitate, washed, and then sonicated. The supernatant was centrifuged to obtain Ti3C2T with pH 5-6. x MXene solution; Step 2: Take a certain amount of MXene, add water and ethanol to obtain an MXene solution of a preset concentration, then add pyrrole and ferric chloride ice crystals, react for 6-10 hours to obtain PPy-MXene composite hydrogel; Step 3: Immerse the PPy-MXene composite hydrogel in ultrapure water to remove excess salt, take out the composite hydrogel and pre-treat it by absorbing water on filter paper, then fully cool it in liquid nitrogen and freeze-dry it to finally obtain a three-dimensional PPy-MXene composite aerogel with metal salt ice crystal polymerization and cross-linking.

2. The method for preparing three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking according to claim 1, characterized in that, The reaction temperature in step 1 is 30-40℃, and the freeze-drying temperature in step 3 is -50 to -60℃.

3. The method for preparing three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking according to claim 1, characterized in that, In step 2, the volume ratio of water to ethanol is 4:

1.

4. The method for preparing three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking according to claim 1, characterized in that, In step 1, Ti3C2T x The concentration of the MXene solution is 12 mg / ml to 22 mg / ml; the concentration of the MXene solution prepared in step 2 is 12 mg / ml.

5. The method for preparing three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking according to claim 1, characterized in that, The ferric chloride ice crystals are obtained by freezing a ferric chloride solution.

6. The method for preparing three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking according to claim 1, characterized in that, The ferric chloride ice crystals are added at 0-5°C.

7. The method for preparing three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking according to claim 1, characterized in that, The mass ratio of MXene to pyrrole is 1:(1.2-1.7); the mass ratio of MXene to FeCl3 is 8:(2-4).

8. A three-dimensional PPy-MXene composite aerogel based on metal salt ice crystal polymerization crosslinking obtained by the preparation method according to any one of claims 1-7.

9. An electrochemical device, characterized in that, It was prepared from the three-dimensional PPy-MXene composite aerogel as described in claim 8.

10. The electrochemical device according to claim 9, characterized in that, The electrochemical device is obtained by laser shaping technology, which uses an infrared laser in an inert atmosphere and has a power of 30W.

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